Sangean ATS-909 / Radio Shack DX-398
Sangean ATS-909 / Radio Shack DX-398, Roberts R861 circa 2004
What is the ATS-909?
What is the DX-398?
The Sangean ATS-909, and the Radio Shack DX-398, is a portable shortwave radio about the size of a large trade paperback. It tunes from 150 kHz to 29,999 kHz and from 88 to 108 MHz in four bands. It can receive single-sideband in true LSB/USB, rather than the simple BFO of most portables of its class, though it doesn't offer synchronous detection. Unlike the Sony 2010, though, the Sangean can tune in 40 Hz steps, though it does not display frequencies at that resolution.
It's got a nice, large, backlit LCD display and a large alphanumeric memory, capable of storing up to 308 stations. The radio comes preprogrammed with over 250 frequencies of international broadcasters. As with the Sony SW-77, alphanumeric tags can be used to designate frequencies. The radio has RDS (Radio Data System) on FM, which will display the call letters of a station or set the clock.
The radio also has a clock with two settable time zones, a sleep mode, a tape out and remote jack, an external antenna jack and an RF gain control.
In all, it's an intriguing little radio.
Is there a difference between the two?"
The Radio Shack DX-398 is identical to the Sangean ATS-909, except for the nameplate. The Sangean comes with accessories that aren't included in the Radio Shack version, namely an AC adapter and a reel antenna. Both radios come with a vinyl case.
Where do I find one and how much does it cost?
The ATS-909 can be found from Grove or C. Crane, among other places. It costs around $260-$280, and this includes a vinyl case, AC adapter and reel antenna.
The DX-398 has been discontinued by Radio Shack, but you may be able to find one on closeout for $150. The catalog number is #20-228, this includes the radio and its case; the AC adapter and reel antenna are not included.
Dave Moisan, N1KGH
Updated April 3rd, 2003
• Taking it Apart
• Anti-chuffing mod
• Removing the Beep
• Removing the detent on the tuning knob
• Finer tuning for single sideband signals
• Improving the AGC
• Putting it back together
• Restoring 76-88 MHz FM
• More diode tricks
• Using a Sony 7600 Speaker.
• Jim Bowlin's 909/398 amp/speaker match modification
• IF Clipping Mod
Taking it apart
The following modifications are courtesy of Rick. and are reproduced with permission from his web site.
1. Unplug the power, antenna, headphone and tape connections.
2. Remove the volume, manual tuning and RF gain knobs by pulling them straight off away from the radio. Be careful not to bend the shafts.
3. Move the whip antenna out of the clipped holding position so that the small screw can be removed from the antenna compartment. Use a small Phillips head screwdriver for this.
4. On the back of the radio, there are five holes with arrows pointing towards each screw. Remove these with a medium tip Phillips screwdriver. Put the whip antenna back in its holding slot.
5. Now is the sticky part: apply pressure to the two radio halves at the top and the bottom so that the tabs inside will unlock. If a tab does not unlock, a small piece of plastic holding the tab will break; it can be glued back in place but the radio can be reassembled without it. Lift up and pull the back of the radio up and toward the top of the radio as you work pulling the bottom half away going left toward the volume knob. This is somewhat awkward but can be done right, if done slowly.
6. Now, if you push in between the volume and tuning control with light pressure the left side should come loose at the next tab. Now push the back up toward the top of the radio a tab in the top left should come free as well as a tab at the top right of the radio. The last tab is at the center of the external connections for power, headphone, rec and antenna jacks and hinges at this plate.
7. The back can now be separated from the radio but be careful--the antenna is connected to the back with about 2-1/2" of white wire. The antenna may be disconnected by removing the radio assemble from the front cover and pulling the antenna connector from the board, but be careful with the red and white speaker wires.
Anti-chuffing Modification
1. Once the back is off, look down on the left side of the board under the tuning knob. Use a magnifier to locate from top to bottom, the surface-mount parts, 224, 334 and 474 and 103 (the 474 and 103 are side by side). Directly below 474 and 103 is a "round" surface mount diode, orange with a black band at the top, soldered vertically onto the board. Next to that diode to the right are 2 leads with solder. The leads are between the round diode and the single leg of a surface mount transistor to the right of the leads.
2. After the leads have been located, carefully power up the radio using the external power supply. Push the up and down tuning and see if the mute goes away when shorting these 2 leads with a screwdriver and see that the correct leads have been located. If this is correct, solder the 2 leads together to disable the muting. You could also install a micro SPST switch if you like. It's surface-mount, so be careful not to overheat when you solder it.
Be advised that this allows all PLL tuning noises to come through while using the radio; to many, this is preferable to the chuff noises. When the freewheel tuning knob mod is also performed, it works much like an old analog radio and greatly enhances the enjoyment and usability of the radio.[pic]
Removing the beep
1. With the radio still disassembled, carefully pull the radio assembly out of the front half of the radio by pulling it up and out. There are no more tabs or screws in the top half. The speaker wires are red and white and only 3" long, so be careful when you lay the front section of the radio aside.
2. Now with a small Phillips screwdriver remove 2 small black screws from the display board. 1 screw is near the time set switch and the other is near the speaker cavity. Now, there are 3 tabs on the bottom under the keypad and 2 on top of the display board just above the LCD. Carefully pull the top and bottom tabs back one at a time, lifting the board with each tab gently until the board is free.
3. The wires to the "beep speaker" are a fine gauge red and black wire soldered to the display near the left side of the LCD. To disable the beep, disconnect the wires or remove the speaker completely, which is held by one small screw.
Removing the detent on the tuning knob
1. There are 6 solder pads on the tuning knob near the LCD display light at the left and just below the power button. Using solder wick or a desoldering tool, remove all the solder from the 4 inside pads first. Then remove all of the solder, from the 2 outside pads with the "ears", or ground of the tuning control. If the solder has been removed, then the control can now be removed from the board.
2. With a fine flat blade screwdriver or knife blade, carefully lift the four tabs on the back of the tuning control. Use a pair of needle nose pliers to straighten them up. When taking the control apart, note how it's assembled.
3. Carefully remove the plastic control housing and post from the metal shell at the same time. Inside the metal shell with "ears" is a copper ring. Remove the ring, after noting how it's assembled. The copper ring has 2 bends and a notch that sticks up on one side on the center of a bend. This, along with the plastic post is what causes the tuning knob to be detented, working in a clicking motion.
4. Using needle nose pliers, gently flatten the notch that sticks up on one side of the ring without smashing the curves in the ring flat. Then re-assemble the control and try turning it in your fingers, holding the assembly together. Make any necessary adjustments to the control before you re-solder it back into the board. If you need to, check it with the tuning knob on the control first. The stiffness of the control is somewhat controlled by how the knob is pushed up to the surface of the radio.
5. After the control has been put back together gently flatten the 4 tabs back into place using the needle nose pliers. Re-solder the control into place on the display board. Check your work and power up the radio to check the manual tuning. You should now be able to tune much easily, possibly with only one finger on the tuning knob. This mod works great!
Finer tuning for single sideband signals
This mod adds a much finer tuning resolution for the slow setting on sideband. I can pretty much zero beat every signal. You will lose the tuning range, but will gain a finer resolution.
Referring to the schematic, attach a 4.5K resistor across the left/bottom and the right solder posts on SVR5. SVR5 is the 48 Hz tuning for the sideband.
This modification does not work for all side band operation. If a signal is too far off zero-beat, the signal will drop off. If that happens, just switch to the fast setting.
Improving the AGC
This mod provided courtesy of Ingo Truppel . Contact him if you have any questions.
Big capacitors are responsible for the slow AGC and they used big capacitors because of the high slope gain of the AGC control circuit.
Now to the changes:
1. C57 on Pin15 of IC1 (TA7758P) should be changed from 22μF to 10μF
2. An additional resistor with a value of 18kOhm has to be placed between Pin15 and Pin17 of IC1 (TA7758P)
3. C11 should be checked--the scheme needs a value of 4.7μF--my radio contained a capacitor with 10μF. 4.7μF is the right value
4. the upper trace to the + terminal of C11 should be cut, so that it is isolated from the circuit. An additional resistor with a value of 4.7 kOhms has to be inserted connecting the + terminal of C11 to the base of Q53. In other words, use a serial connection of 4.7kOhm and 4.7µF instead of 4.7μF for C11
A further change that should be done is to shunt the resistor R7 (68 Ohm) from the lower point of the Gain poti VR1 to be zero. That gives you a control of the input sensitivity down to zero. This is very helpful to receive strong signals especially if you use an external antenna.
Putting it Back Together
1. Carefully re-install the LCD display board into the tabs, they should snap into place when the board is lined up. Remember to put the 2 small black screws back that hold the display board. If the speaker wires were removed, reconnect them with the correct polarity and check the antenna connector. Make sure the LCD screen and plastic faceplate inside the front cover are clean.
2. Lay the radio assembly back into the front cover checking the speaker wires for pinching and the alignment of the time-set and MW step buttons, along with the battery compartment ribbon. When putting the back cover on, the switch covers should line up with the switches and the connector holes should line up with the connectors on the radio before dropping the cover in place as well as all the connectors at the side of the radio. Remember to pull the battery ribbon up through the hole.
3. Put the four long screws at the back of the radio in place. Then move the antenna out of the clipped holding position so that the small screw can be replaced back into the antenna compartment. Put the antenna back and reinstall the batteries if used.
4. Check that all the buttons and switches are functioning properly. Reinstall the volume, manual tuning and AM-RF gain knobs. Reposition the tuning knob in or out of the case to adjust the tension to the control. That's it! You now have a new radio.
Restoring 76 MHz FM band
This modification extends the lower end of FM reception to 76 MHz.
PROS: Useful if you are planning a trip to Japan or if you want to pick up the audio of TV channels 5 and 6. Or if you just want to see what's down there.
CONS: There are many image signals below 88 MHz (this could be why the extended FM is not the factory default). Most of the image signals are from broadcasts 21.4 MHz higher. For example a broadcast at 100 MHz will also be picked up at at 78.6 MHz.
TOOLS: You will need a small phillips screwdriver, a soldering iron and solder wick (or a desoldering tool).
PARTS: One 1N4148 signal diode (a 1N914 should work as well).
Procedure:
Open up the case
Remove the five phillips head screws from the back of the unit (including the one hidden under the antenna) and pry the two halves of the case apart. See the previous section on disassembly for details and warnings. You don't need to remove the batteries if you can remove the front part of the case from the rest of the unit. Be careful of the speaker leads and the leads to the buzzer. You may want to mark these and remove them temporarily.
Remove the smaller Control printed circuit board
Remove the two small phillips head screws holding the board. Release the five plastic hooks at the top and bottom edges of the board. Lift the board out. I found it to be easiest to disconnect the the two coax wires via the connector at the main PCB. This allows the control PCB to "hinge" on the remaining wires and lie flat in front of the rest of the unit. With the back of the control PCB facing upward.
Remove the metal shield
Most of the back of the control PCB is covered by a metal shield. If the shield has a bunch of holes in it, you are on the wrong side. It is soldered to the PCB at about 10 locations spaced around its edges. Remove the tape that holds some wires to the shield. Unsolder all the connections on the edge of the shield. Make sure you don't melt any plastic or wires during this process, especially when working on the edge that is closest to the body of the unit. After the connections are unsoldered the shield lifts right out. There is no bending of metal needed.
Install the diode
The diode to install is called D310 but there are no markings on this side of the PCB. For orientation, the multi-wire connectors are at the bottom of the board, and the large uP chip is up near the top of the board. Look for three diodes lined up side by side halfway down the board, and then look for four empty solder pads just to the left of the diodes and down slightly:
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Add the new diode as indicated. It should be mounted in the same direction and orientation as the three nearby diodes. It is a surface mount connection, but I had no trouble using a regular diode by making its leads short and bending them to fit the pads.
Test
Before closing up the unit you can hold the control PCB board vertically and reattach the connector that has the two coax wires going to the main PCB. Power the unit up and see if your FM range now goes down to 76 MHz.
Reassemble
Solder the shield back in place. Retape the coax wires to the shield.
Insert the control PCB back into the unit. Be sure that the wires between the two PCBs don't prevent the board from seating properly. Snap the five plastic hooks in place. Remember to put back the two small screws that hold the control PCB. Reattach the buzzer and speaker if you have disconnected them. Carefully put the two halves of the case together. Make sure all the slide switches are working properly. Put the five screws that hold the halves together back in.
That's it. Again, check out for more details regarding opening up and closing up the case.
-- Jim Bowlin April 10, 1998
Other Diode Mods
There are a total of six extra diodes that can be installed, according to a small note on the schematic.
D322 FM down heterodyne
D316 FM step 50 KHz
D310 FM 76-108 MHz
D314 FM 64-74, 87.5-108 MHz
D311 and D312 are used to control the AM coverage. The factory default is both diodes absent which gives the widest coverage:
LW MW SW
153-519 520-1710 1.711-29.999
The only other configuration that gives almost full AM coverage is adding diode D311 which changes this to:
LW MW SW
153-519 530-1602 1.603-29.999
So adding diode D311 will shift some freqs from MW into SW. And chop off the lowest 10 kHz of MW coverage. other diode configurations reduce the AM coverage even more.
-- Jim Bowlin
Using a Sony 7600 Speaker
Peter writes, on the 909's speaker:
One thing I noticed when I was pulling apart the 398, though, was that they'd clearly intended to use a much better speaker than the one they ended up using. The 7600 speaker turns out to be (likely) what they were planning - they left enough knockout in the circuit boards for a speaker with a 1 3/4" magnet, which just happens to be the 7600 magnet.
I called Sony after figuring that one out and mail ordered a replacement speaker for a 7600g; it fits perfectly into the case, and sounds a bit better to my ear than the old one. Later this week, I'll actually take the radio down and listen to it side-by-side against an unmodified radio.
Oh, why'd I mail [pic]order a speaker? try finding *anyone* who's actually selling a 3" round speaker these days that's thin enough to fit into the case, and yet has a better magnet than the 398....
Call Sony Parts at (800) 488-7669 or (941) 768-7669 (voice). Their fax number is (941) 768-7790.
[Just be careful of the magnetic field. A speaker with a too-large magnet may desensitize the radio, just like with the GE Superadio--DM]
Jim Bowlin's 909/398 amp/speaker match modification
This might be useful to some people and/or aliens:
Locate the power amp ICs: IC4 and IC5, they are pin SIPS located on the main PCB between the speaker hole and the batteries. Then find the combination of C188 and R204, C188 is a small beige surface mount square and R204 is a black surface mount rectangle with "333" on it. They are located next to each other vertically almost between the two ICs and horizontal just to the knob-ward side of the ICs. If the battery compartment is at the "top" then these two components are mounted vertically. The bottom connection is to a wide PC run which is at ground. The other side of the components go to a land that has a nice fat wire sticking out if it which is good for soldering to. If you touch this land with a finger or small wire, you will hear a LOUD 60 Hz hum. Solder a 2.2k resistor between this land and ground. The wide pc runs in this area are grounds. Don't do any soldering with the power on!!!
Next find C148 and R179. They look just like toe other two. They are between the first pair and the ICs. But they are not right next to each other.
Again one side of each goes to ground and the other side goes to a land that causes a LOUD hum when touched. This land also has a fat wire sticking out of it that is good to solder to. Another 2.2k resistor goes between this land and ground.
You may want to roll off the high frequency response. To do this add a cap in parallel with each resistor. A value of 0.005 uF will start the rolloff at about 15KHz. If you use polarized caps, make sure the negative side goes to ground.
IF Clipping Mod
Rick:
I have noticed clipping distortion on both of my 398's, particularily on certain MW stations. I have tried the main amp. & pre-amp reduction mods, but they didn't cure the clipping distortion. (It sounds like the speaker is breaking up.)
Last night I found a simple solution. Connect a 1K ohm resistor between IC1 pin #9? and ground. (I will try to confirm the pin# tonight when I have time to look at it more closely) It's the left side, 2nd from the bottom. IC1 is located up and a little right from the negative battery terminal. It also cured the distortion present when plugging in headphones in the line out jack. I'm not exactly sure what it reduced. I think it has something to do with the IF. Any users out there who could confirm?
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David Moisan
dmoisan@
Copyright © 1999-2003, David Moisan
Last Updated on April 4th, 2003
About
Does the 909 have birdies (spurious signals)?
Yes. The 909 has two strong birdies at 27.022 MHz and 27.472 MHz, and several others at 17.865 and 18.165 MHz.
Are the station memories really permanent like the manual says?
No. The station memories can be changed.
• Pick the frequency you want to change.
• Enter the new frequency.
• Hit the M key.
• The display will say "MEMOFULL".
• Hold down the M key.
The new frequency should now be stored in memory.
How does the priority button work?
The priority function is not well explained in the manual, and it behaves differently depending on what band is involved. On MW, LW and FM, the priority button has its own memory location, so you can store a station to it like any other memory.
On SW, though, the priority button calls up an already existing station memory; it does not store a station itself, but only the reference to a station in the memory pages.
To set a priority station in MW, LW or FM bands:
Tune to the station you want. Hit the M key. Hit the PRIORITY key (that key that looks like a "1" and an arrow.) That's it. When you next hit the PRIORITY key, the station you stored will come up.
To set a priority station in the SW band:
First, the station you want to hear must already be stored. Find a empty page (usually page 29) or overwrite a memory location and store your station there. Then hit M and PRIORITY. As long as the station is stored in "regular" memory, the PRIORITY key will call it up.
How do I use the timers?
Rocky, KA7EII@, offers this explaination:
First of all, timers 1 and 2 will turn off the radio after one hour and timer 3 will allow the radio to play until you turn it off.
Turn the radio on and tune to the station that you want the radio to come on to. You can use any frequency and mode on SW or any AM, FM or LW station. Let's say I want to wake up to KNX-1070 at 5:20am.
Now press the MEMO button and the word "MEMO" will flash on the display. Press the TIMER 1 button and the radio will beep. Press TIMER 1 again and the word "timer" will flash on the display. Use the AM MODE button to select radio (you should see the musical notes on the display).
Now use the numbers on the keypad to enter the turn on time. For my example I pushed 5, 2 and 0. Be sure to use 24-hour time. Now press ENTER and "TIMER 1" will show on the display. To check the status of the timer at any time just press the TIMER 1 button and you will see the time and frequency that the radio will turn on to. Press TIMER 1 to go back to regular radio operation. To delete the timer just press the TIMER 1 and CLEAR. To turn the timer back on again just press TIMER 1 button and the "enter" button.
The timers also have a "snooze" function. When my timer 1 comes on at 5:20am and I want to get a little more sleep, just press TIMER 1 button when the radio comes on and it will turn off and turn on again in about 5 minutes. Timers 2 and 3 also have the "snooze" feature.
A favorite of radio enthusiasts is the Sangean ATS-909, also known as the Radio Shack DX-398, Siemens RK777, and Roberts R861.
This page is a work in progress.
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I own the Radio Shack version of this radio, the DX-398. Adjustments are best performed with the correct test equipment. Methods shown here are directed toward those without access to such equipment. It's important that the radio be at normal operating temperature before making adjustments.
[pic]Chuffing / Anti-Muting Modification (correct method)
By default the radio mutes audio while you change frequencies. Some people, like myself, prefer this not occur and like to hear the audio as frequency is changed.
I strongly advise not performing the mod you may find on other web sites and discussions. There's a mod involving shorting two circuit points next to a diode. The mod works but not as well as it should and is not healthy for the radio. Problems include display backlight flickering and a huff or pump in the audio as frequency is changed, excessive noise when selecting a memory, random erroneous RDS indications, random shut-downs, and eventual system failure. This mod places an excessive load on the CPU. There is a better and just as simple method.
Along the bottom of the rear circuit board are 3 rows of pins, 2 of these are for connectors between the two boards. The leftmost pin of the leftmost connector when looking at the solder side is the mute pin. Remove the solder from the connection thoroughly. Jiggle the pin slightly to make sure it is free. The connection is now open and the muting will not occur as you change frequencies. This method makes it very easy to revert to the original condition.
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Backlight LED changes: Some people have changed the backlight LEDs to change color or brightness. This is a fun and relatively simple modification. The "Super 909" radio uses blue LEDs. The radio uses two 3mm round LEDs. Note that some LEDs require a higher operating voltage than "standard" types. The factory green, while fairly bright, are a standard LED and light at full brightness at around 1.5 to 2 volts. High brightness LEDs typically operate at around 3 volts. Therefore you may need to make some additional changes to get them to work well. I installed 2 high brightness white LEDs in my radio. The factory wiring places the LEDs in series applying about 1.5 volts to each. Changing the setup to parallel places about 3 volts to each, perfect for high brightness types. I made the change by leaving one LED leg up from the board and bringing a wire around the top of the display from one side to the other. This places the LEDs in parallel and they each see the 3 volts the radio supplies for the display. For clear lens LEDs you may want to rough them up a bit to add some difusing. Rubbing or twisting the LED a bit on a Scotch Brite pad will do the trick.
Here my radio has the white LEDs on showing it tuned to KCJJ, Iowa City, 1kW at night, a tad over 200 miles away at 1AM local time with a weak but listenable signal. The display actually looks a little better than in the picture. The camera doesn't quite see what the eye does. I much prefer the readability of the display with the white LEDs versus the factory green.
[pic]
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External Antenna Connection. I use a 1/8 phone to F adapter. It's a convenient way to get from that small jack to coaxial cable. The jack is a TRS type, while the adapter is TS. This shorts the Ring and Sleeve. Doing so disables the internal antenna for MW and uses the external only.
[pic]
|Speaker upgrade/replacement: The factory speaker is a typical small equipment speaker. The|[pic] |
|radio actually sounds pretty good considering how small it is. However a better speaker |[pic] |
|can improve your listening experience and the factory component has the habit of wearing | |
|out after a few years. If you choose to upgrade the speaker there is room for a larger | |
|one. Be careful in choosing a speaker, too large a magnet will apply a strong field to | |
|nearby components that are sensitive to magnetism. The radio uses a 3 inch / 77mm round | |
|speaker, rated 8 ohms, 3 Watts. It's 76.87mm diameter and 26mm deep. It's unlikely you'd | |
|ever send 3 Watts so the more readily available 1 Watt speaker should be just fine. | |
|Pictured is the factory speaker and the "hole" where it fits into and a replacement with a| |
|much superior magnet. The replacement here has a 30.2mm diameter magnet. | |
| | |
|As of this writing Digikey has a couple of speakers available, sold as singles, that will | |
|fit the task. | |
|CUI model GF0771 paper cone and GF0771M mylar. These have a 32mm magnet. The mylar is more| |
|expensive but should be more durable, has better moisture resistance, and the specs offer | |
|slightly higher frequency range. The factory wiring ties the speaker's frame to the - lead| |
|which is chassis ground. I've connected the replacement speaker to the terminals only | |
|leaving the frame isolated without any adverse results. If you're in question or | |
|experience problems you could duplicate the original orientation. | |
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Tweaking AGC: If you use the radio a great deal, especially for single side-band, you'll want to slow down the AGC. There's mods posted on the web to speed up the AGC. This doesn't make much sense because it's already much to fast. If you listen to an SSB signal of any significant signal strength you'll experience 'pumping' of the audio and noise will fill the softer audio segments. Remember in SSB there's no carrier, only modulated audio. The AGC being too fast quickly drops the gain as modulation increases and raises raises the gain as modulation falls. So noise fills the space between every syllable. This will drive you mad. Performing this mod requires soldering and exchanging a component. It should be noted that complaints about the AGC being too slow seems to be with regard to the attack speed. I agree, and that can be corrected. But I find the decay time being too fast is much more uncomfortable. The radio has a high slope gain and the AGC appears to have been chosen for this reason. Making this mod will make the radio noisy when turning it on and selecting presets. I plan on revisiting this issue and try to determine how to address creating a faster attack and slower decay. I'll have to check into the operation of the IC. Making C57 larger will slow the AGC. But it's a trick to get a larger cap in the same space.
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Tweak tuning: To insure your radio is tuned to the frequency it says it is you'll want to tweak it up. This is especially valuable for SW listening. And tweaking it for SW may effect tuning for the other band so choose the one most important to you. Just below the display there's a small variable capacitor near a typical crystal identified as TC301. This is a fine adjustment of the reference oscillator that get's to the PLL. You could/should use a frequency counter for this task and tune to 4.332MHz. Or tune to a known reference station such as WWV and tune for best audio. I chose 10Mhz as I spend most of my time in the lower portion of the SW range where 15MHz would otherwise be nearer the center of the radio's range. Tune up and down 1kHz from the station and listen. The change in audio pitch should be identical at both above and below the test frequency. When it sounds even you've got it near perfect. It should be good enough for enjoyable use.
The other adjustment, TC302, is fine tuning for the 32.768 kHz crystal oscillator for the clock. I wouldn't mess with it unless you find your clock isn't very accurate. As often as I change batteries I don't care how accurate the clock is and I always have a time signal station.
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Tweak SSB oscillators: You may find when using SSB that upper or lower sideband doesn't seem to perform as it should. For example when you hear a SSB signal while in AM mode and you select LSB the signal vanishes and you have to search up or down a bit to relocate it. Then you discover it must be USB, and again it vanishes and you have to tune around again. This makes SSB listening cumbersome. There's an adjustment for each. If you're centered on an accurate AM station, assuming the radio tunes accurately, and you switch to lower or upper side band you should not hear the 'beat' tone. Audio will get 'weird' because you're not in AM, but if you get a steady tone the SSB oscillator is beating with the carrier. We don't want this. Having this accurate is helpful also for determining the precise frequency of some stations. This could/should be performed with a frequency counter. However again tuning by ear can work out quite well. Again WWV is useful for this adjustment and is best done during a minute they are not transmitting the constant tone. VC5 adjusts USB to 452kHz and VC4 adjusts LSB to 448kHz (2kHz away from the 450kHz IF). Tune them slowly while on the reference frequency, again I used 10MHz, and listen for the beat tone to disappear. Compare LSB and USB a few times on frequency and equal distance above and below. Then hit the amateur bands and find some SSB. When you find a signal while in AM switch to both LSB and USB and the signal should remain. It may not be perfect and that's what the fine tuning in this mode is for. Locking on should only take a few 'clicks' of the tuning knob. These adjustments are on the rear board.
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There are several more modifications you can perform. I don't recommend the FM range mod, unless you live where the FM band is outside of 87.5-108 Mhz. (Japan for example) There's no particular advantage. There's a mod to move some of the MW band into SW, I would leave that as is also.
Upgrading filters is up to you. They're getting more difficult to obtain but inserting a more narrow filter can produce nice results. However, because the radio displays RDS info from FM, using too narrow of filter will hinder that operation. If you're not concerned with RDS go ahead and make the change. You may also choose to install an RCA jack or another type, SMA perhaps, for a better external antenna connection.
I personally like the detents in the tuning knob, but you can modify it to turn smoothly.
The SSB fine tuning mod gives you smaller steps for more fine adjustment but reduces the tuning range. The factory setup I find is good enough for most signals and allows you to tune continuously.
Here's a very useful "trick". According the the user manual the preset memories are permanent. However you can override any of them and completely customize your radio. To change an already used memory simply press the M key. The display shows MEMFULL. Continue holding the M key and the current tuning will over write the contents of that memory. Doing this will sometimes shift other memories around. You can always clear any memories you wish as well. This is helpful to keep memories for a particular station or whatever you use them for in the order you want them.
A note of caution, (learned the hard way) the power connector is a "reversed" type barrel, that is the positive is on the outside and negative is inside. The negative is equal to the system ground. Using a plug-in adapter with a 4-way style connector (one of those one connector for all devices sort of thing) set up for reverse mode places the voltage on the outside metal of other plugs barrel and sleeves. (it would be on the tip of 1/8 and micro phone plugs too in normal mode) That alone isn't the big problem. Using a headphone plug made of metal poses the problem. The outside or shield of the headphone plug may contact the barrel or sleeve of the 4-way power plug causing a short THROUGH THE RADIO. This will kill the circuitry that detects the power input to switch off battery. You are left with battery only operation.
Also, it's a good idea to keep the radio out of intense light. If you let direct sun light hit the display on a hot day after a while all segments will show, even with the radio off. Left longer the entire display will black out. It has always returned to normal afterward for me but I don't know if left in the hot sun for longer periods will cause permanent damage.
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